Communications with a Haptic Interface Device from a Host Computer

1. A method of communicating information from a host computer with a haptic device, comprising: a) Transmitting from the host computer to the haptic device an Initialize packet, where an Initialize packet comprises a sequence of bits having subsequences, in the following order: i) A subsequence indicating the start of a packet; ii) A subsequence identifying this packet as an Initialize packet; iii) A subsequence indicating a start code value for a sequence of code values; iv) A subsequence indicating a message; v) A subsequence indicating the end of a packet; b) After transmitting the Initialize packet, then transmitting from the host computer to the haptic device a Start packet, where a Start packet comprises a sequence of bits having subsequences, in the following order: i) A subsequence indicating the start of a packet; ii) A subsequence identifying this packet as a Start packet; iii) A subsequence indicating the start code value; iv) A subsequence indicating a message; v) A subsequence indicating the end of a packet; c) After a packet has been received from the haptic device at the host computer after the transmission of the Start packet, then transmitting from the host computer to the haptic device a first Command packet; where a Command packet comprises a sequence of bits having subsequences, in the following order: i) A subsequence indicating the start of a packet; ii) A subsequence identifying this packet as a Command packet; iii) A subsequence indicating the code value in the sequence of code values having a predetermined relationship to the code value in the previous packet transmitted from the host computer to the haptic device; iv) A subsequence indicating a message; v) A subsequence indicating the end of a packet; d) After a packet has been received at the host computer after the transmission of the preceding Command packet, then transmitting from the host computer to the haptic device a subsequent Command packet.

2. A method as in claim 1 , wherein the sequence of code values is a sequence of pseudorandom numbers determined using the start code value as the seed for a pseudorandom number generation method.

3. A method as in claim 2 , wherein the pseudorandom number generation method comprises one or more of the Mersene Twister method, the Yarrow method; a Linear Congruential Generator; a pseudorandom number generator using a Linear Feedback Shift Register; and a multiply-with-carry method.

4. A method as in claim 1 , further comprising repeating step d one or more times.

5. A method as in claim 1 , further comprising determining if the host computer receives a packet from the haptic device that does not contain a valid code value, and, if so, causing the host computer to enter an error state.

6. A method as in claim 5 , wherein causing the host computer to enter an error state comprises communicating an error to at least one of (a) a user of the host computer, and (b) a supervisory or error management program on the host computer; and communicating to the haptic device commands to enter a Safe mode.

7. A method as in claim 1 , wherein the host computer transmits packets at a rate of at least 10 per second.

8. A method as in claim 7 , wherein the host computer transmits packets at a rate of at least 50 per second.

9. A method as in claim 1 , wherein the code value in the Command packet is the ith code value in the sequence, and the code value in the next Command packet is the (i+2)th code value in the sequence.

10. A method as in claim 1 , further comprising determining whether a packet received in response to a Command packet has a code value in the sequence of values immediately after the code value in the Command packet.

11. A method as in claim 1 , further comprising determining whether a packet received in response to the Start packet has the code value in the Start packet.

12. A method as in claim 1 , further comprising determining the first Command packet in part from information in the packet received in response to the Start packet.

13. A computer-readable medium having thereon instructions for causing a computer to communicate with a haptic device according to claim 1 .

14. A method as in claim 1 , wherein: a) The subsequence of bits identifying a packet as an Initialize packet is 64 bits in length; b) The subsequence of bits identifying a packet as a Start packet is 64 bits in length; c) The subsequence of bits identifying a packet as a Command packet is 64 bits in length; d) A method as in claim 1 wherein the code values are 64 bits in length.

15. A method as in claim 1 , wherein a subsequence identifying a packet as an Initialize packet is the same as a subsequence identifying a packet as a Start packet.

16. A method as in claim 14 , wherein a) The subsequence of bits identifying a packet as an Initialize packet is 4E 77 6D 6C 6C 6C 6F 4D in hexadecimal notation; b) The subsequence of bits identifying a packet as a Start packet is 4E 77 6D 6C 6C 6C 6F 4D in hexadecimal notation; c) The subsequence of bits identifying a packet as a Command packet is 61 43 4F 6D 6D 41 4E 44 in hexadecimal notation.